I've been working on the Elemental XMLs a bit and tried to introduce a few features to the game (abilities and spells, for instance). However, quite a few basic features could not be implemented with the XML tags that currently exist. I think this could be fixed with a mild-to-moderate amount of work, although since I haven't seen what the engine actually looks like in the C++ code, I cannot tell for sure.

Here's a list of what could be useful for us XML sculptors:

-Condition pre-requisites: these would check that a certain UnitStat (including a custom one) has a certain value (or doesn't, or is below/above a certain value). This could be useful when checking that the target is mounted (spearmen) or is a dragon (dragonslayers), for instance. This is also a good way to prevent "buff stacking" for those who'd like abilities that "buff" another target to not be stackable.

-Triggers: Tags that allow a certain effect to happen when *something* happens in the battle (or on the map), the "something" depending on the map. Very useful for passive abilities. We need this! (but it's the most time consuming part of my list, I'd say)

• Secondary effects that are triggered whenever the target is hit. Like the "procs" in MMOs. for instance, you could have a sword that has a chance to deal additional damage. Or that starts a poison effect on the target. Or lowers one of its attributes. 
• Effects that are triggered when an enemy enters or leaves a square surrounding the unit/item/prop. Think "attack of opportunity" for those of you that played D&D3 (for the others: attacks you can make when someone tries to move past you without paying attention to you).
• Effects that are triggered when being attacked. Or missed. Or when you miss. Or when you dodge. Or when you skip turn. Or when a unit dies on the battlefield. Or when you kill a unit on the battlefield.

-A tag that gives us access to the last damage dealt or the last damage dealt/damage received. We can use it for life-leech/retribution/ablative armors-style  abilities and spells.

-Give us a way to remove a piece of equipment or a spell/effect/ability for a small time. Used in disarm/dismount/disenchant.

-Introduce a way for us to roll 1DN/xDN in the calculate tags. We can use it for effects that trigger randomly.

I don't know if those requests are realistic, but they'd improve the moddability of the game by leaps and bounds, at least until the python API comes along. But the latter isn't going to be here anytime soon as I understand it, so throwing us a bone could be nice. 

Any other suggestions, Elemental players?